Re: [PATCH RFC 4/4] scsi_mq: enable runtime PM

From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Alan Stern <stern@rowland.harvard.edu>,
	linux-pm@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Christoph Hellwig <hch@lst.de>,
	Bart Van Assche <bart.vanassche@wdc.com>,
	"James E.J. Bottomley" <jejb@linux.vnet.ibm.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	linux-scsi@vger.kernel.org
Subject: Re: [PATCH RFC 4/4] scsi_mq: enable runtime PM
Date: Wed, 11 Jul 2018 19:14:09 +0200	[thread overview]
Message-ID: <20180711171409.GC3500@lst.de> (raw)
In-Reply-To: <20180711162906.14271-5-ming.lei@redhat.com>

> @@ -3770,7 +3770,7 @@ EXPORT_SYMBOL(blk_finish_plug);
>  void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
>  {
>  	/* not support for RQF_PM and ->rpm_status in blk-mq yet */
> -	if (q->mq_ops)
> +	if (q->mq_ops && !(q->tag_set->flags & BLK_MQ_F_SUPPORT_RPM))
>  		return;
>  
>  	q->dev = dev;

This should go into a block layer patch, not a scsi one.

> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index 41e9ac9fc138..fa4667aa4732 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -2306,7 +2306,8 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost)
>  	shost->tag_set.queue_depth = shost->can_queue;
>  	shost->tag_set.cmd_size = cmd_size;
>  	shost->tag_set.numa_node = NUMA_NO_NODE;
> -	shost->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
> +	shost->tag_set.flags = BLK_MQ_F_SHOULD_MERGE |
> +		BLK_MQ_F_SG_MERGE | BLK_MQ_F_SUPPORT_RPM;

As far as I can tell only ufs and libata support runtime PM, so
we should probably only enable it for those.